pub fn morton_encode2(x: u32, y: u32) -> u64 {
    let mut x = x as u64;
    let mut y = y as u64;

    x = (x | (x << 16)) & 0x0000FFFF0000FFFF;
    x = (x | (x << 8)) & 0x00FF00FF00FF00FF;
    x = (x | (x << 4)) & 0x0F0F0F0F0F0F0F0F;
    x = (x | (x << 2)) & 0x3333333333333333;
    x = (x | (x << 1)) & 0x5555555555555555;

    y = (y | (y << 16)) & 0x0000FFFF0000FFFF;
    y = (y | (y << 8)) & 0x00FF00FF00FF00FF;
    y = (y | (y << 4)) & 0x0F0F0F0F0F0F0F0F;
    y = (y | (y << 2)) & 0x3333333333333333;
    y = (y | (y << 1)) & 0x5555555555555555;

    x | (y << 1)
}

/*
 * Decoding.
 */
fn unpack(mut x: u64) -> u32 {
    x = x & 0x5555555555555555;
    x = (x | (x >> 1)) & 0x3333333333333333;
    x = (x | (x >> 2)) & 0x0F0F0F0F0F0F0F0F;
    x = (x | (x >> 4)) & 0x00FF00FF00FF00FF;
    x = (x | (x >> 8)) & 0x0000FFFF0000FFFF;
    x = (x | (x >> 16)) & 0xFFFFFFFFFFFFFFFF;
    x as u32
}

pub fn morton_decode2(d: u64) -> [u32; 2] {
    [unpack(d), unpack(d >> 1)]
}